Electronic control systems have been employed to control various functions of bathing installations such as pools or spas. For example, the control system can control the pump which recirculates water in a spa. There can be malfunctions in which the pump continues to run, even though the controller has commanded it to the off condition, e.g. when the pump relay contacts providing power to the pump have fused together. When this occurs, the water temperature can slowly rise as the pump runs, potentially creating a scalding threat to a user.
A concern for a spa or pool is that the suction generated by the water flow may hold a person against a water outlet.